Electricity economic feasibility

Note that a five-layer solar-cell is proposed. However, cost-considerations may make this type of solar cell impractical since the cost of electricity will be too much. A three-layer type of solar-cell has been built which had an efficiency of about 39% (consisting of Si, GaAS and GaN). But until the price of other energy sources mount, or until the cost of gallium-based materials drops, a layered solar-ceU will not be economically feasible. 

This is not to say, however, that these processes always are economically feasible, since electric power could stiU be overly expensive witness the scarcity of drinking water in many coastal regions. 

ED appears to be an inefficient method to recover free citric acid because of its low electric conductivity (Novalic et al., 1995). As it is converted into the monovalent (at pH ca. 3), divalent (at pH ca. 5), or trivalent (at pH about 7) citrate anion, there is a significant increase in the electric conductivity (%), the latter increasing from 0.95 to 2.18 and to 3.9 S/m, respectively, in the case of an aqueous solution containing 50 kg/m3 of citric acid equivalent (Moresi and Sappino, 1998). By increasing the pH from 3 to 7, e reduced about eight times, the solute flux (JB) practically doubled, while the overall water transport (/w) increased 3-4 times. The latter partly counterbalanced the greater effectiveness of the electrodialytic concentration of citric acid at pH 7 with respect to that at pH 3. Table XV presents a summary of the effect of current density ( j) on the main performance indicators of the electrodialytic recovery of the monovalent, divalent, or trivalent ionic fractions of citric acid (Moresi and Sappino, 1998). All the mean values or empirical correlations of the earlier indicators were useful to evaluate the economic feasibility of this separation technique (Moresi and Sappino, 2000). 

Suppose a scientist, say a physical chemist, discovers a new principle by which solar energy canbe converted into electricity. The engineer is required to make this principle work in practice. The economist will be needed to assess the economic feasibility, which should include ecological aspects. But even then the sociologist may be needed to explain why people don t buy it. If the innovation serves a global interest, a multidisciplinary effort with participants also skilled in communicating the essence of their discipline to each other will enhance the successful introduction and acceptance of the innovation. 

However, this method is not economically feasible for all applications due to power requirements. Electrolysis has been used for long wherever electric power is available cheap or pure hydrogen was needed or where there is a renewable energy source available. 

Power plants to burn scrap tires involve large capital investments and annual operating expenses. However, plants located near large supplies of tires can be feasible. A key variable in determining economic feasibility for these plants is the buy-back rate granted by the utility. In areas of the country where the rate is high, such as California and the northeast, power plants are feasible. The buy-back rate is the rate the utilities pay for electricity generated from alternative fuel, and reflects the fuel and other costs avoided by the utility. 

As discussed above, there are currently operating facilities where the combustion of tires and tdf has proven to be profitable. The economic feasibility of tires-to-energy plants depends on the buy-back rate for the electricity. For tdf consumed at cement kilns or pulp and paper mills, the economic feasibility depends on cost savings over competing fuels. Only a substantial annual cost savings justifies modifying a plant to handle tdf. The next section discusses the noneconomic barriers that must be considered once it has been determined that tire combustion is economically feasible. 

At the U.S. Forest Products Laboratory, many of the research programs involve fire-retardant-treated wood. This has included extensive basic study of pyrolysis and combustion reactions of wood and its components and the effects of chemical additives on these reactions (15,24-26,28,29,66). A cooperative study (9) with the Division of Chemical Development of the Tennessee Valley Authority, showed the effectiveness of liquid ammonium polyphosphate fertilizers as fire retardants for wood. The commercial use of these products, made from electric furnace superphosphoric acid, has been shown to be economically feasible. Work has been completed by Schaffer (33) on the rate of fire penetration in wood treated with different types of chemicals. Some results of this study are reported elsewhere in this paper. 

When looking for an economically feasible enzymatic system, retention and reuse of the biocatalyst should be taken into account as potential alternatives [98, 99]. Enzymatic membrane reactors (EMR) result from the coupling of a membrane separation process with an enzymatic reactor. They can be considered as reactors where separation of the enzyme from the reactants and products is performed by means of a semipermeable membrane that acts as a selective barrier [98]. A difference in chemical potential, pressure, or electric field is usually responsible from the movement of solutes across the membrane, by diffusion, convection, or electrophoretic migration. The selective membrane should ensure the complete retention of the enzyme in order to maintain the full activity inside the system. Furthermore, the technique may include the integration of a purification step in the process, as products can be easily separated from the reaction mixture by means of the selective membrane. 

Although the United States pulled out of the collaborative group in the late 1990s, it rejoined in 2003. The cost of ITER is thought to range from 5-8 billion, and its construction would take 10 years. When ignition and parity are finally achieved and understood, spending will need to be substantially increased to establish commercial feasibility. It is now realized that electricity from fusion will be more costly than that from fossil and fission processes. It is only as these resources are depleted that fusion will become economically feasible. 

The annual operating costs are also shown in Table 3. The raw materials costs were estimated from the average purchase cost of crude olive oil in Portugal in 1994. Supplies were empirically calculated from the scale-up study and include water, electric power, fiiel, maintenance, assurances, transports and expedient articles. The labour costs were determined for 4 shifts of 2 persons each, plus supervising personal. With a depreciation time of ten years and an interest rate of 10%, the total annual capital costs was estimated to be 212PTE/kg of oil feed. Several other economical indicators, such as the internal rate of return of the plant, showed a promising economical feasibility for this project. 

Two case studies are presented in which polymer nanotube composites are proposed as replacements for conventional materials. We evaluate the technical and economic feasibility of using them as smart materials for strain gauges thus, exploiting their electrical properties, and as structural materials for aircraft panels bringing into play their mechanical properties. Our analysis shows that as new strain gauge materials, polymer nanotube composites offer many advantages. As a possible replacement for aluminum in an aircraft panel, it is found that a hybrid composite of (Epoxy 33% carbon fabric + 30% carbon fibers + 3% CVD-MWNT) is an attractive candidate. 

By 2040-2050, natural gas reserves will be in very short supply, and the production of coal will quite likely be approaching peak production levels.19. While nuclear power plants are a source of large scale electricity generation, there exist major concerns regarding uranium supply (without breeder reactors), safety, waste disposal, and nuclear weapon proliferation. Therefore, it is prudent to explore the economic feasibility of other fuel sources such as PV electrolytic H2 for centralized, electricity generating plants. 

From the results presented in Table 7.A, the levelized electricity price for electricity produced by combined-cycle power plants fueled with first generation H2 is too expensive to be considered economically feasible. However, if the 60-year PV module operating life model proves relevant, then the levelized price of electricity generated by combined-cycle power plants using second generation H2 as a fuel source could be as low as 0.15-0.17/kWh. These electricity prices provide some assurance that if other options fail to meet electricity demand in the post-2040 period, dispatchable PV electricity will be a feasible option. Clearly, further progress in PV cost reduction, a near certainty by 2040, will reduce the price of electricity generated by H2 fueled power plants. 

Electrolytic Decomposition of Water. This industrial process is economically feasible in localities where low-cost electricity is available, where there is a demand for oxygen as well as for hydrogen, and where the hydrogen is required to be completely free from carbon compounds. Sodium and potassium hydroxides are the practicable electrolytes in this process. 

It takes 15 kWh (kilowatt hours) of electrical energy to produce 1.0 kg of aluminum metal from aluminum oxide by the Hall-Heroult process. Compare this value with the amount of energy necessary to melt 1.0 kg of aluminum metal. Why is it economically feasible to recycle aluminum cans (The enthalpy of fusion for aluminum metal is 10.7 kj/mol and 1 watt = 1 J/s.)... 

Very pure hydrogen can be produced by the electrolysis of water (see Section 11.7), but this method is currently not economically feasible for large-scale production because of the relatively high cost of electricity. 

This is yet another energy source that could become economically feasible if the new high-temperature superconductors prove out. In converting various sources of energy into electricity, scientists have concentrated their research and development efforts on rotating types of equipment. MHD power, on the other hand, requires none of the moving parts typical of a conventional generator. It... 

In many cases, membrane processes seem to be the most energy efficient separation processes available for industry. However, the costs related to cleaning or replacement of membranes, the need for skilled personnel, and the associated turn down costs determine their economical feasibility. Table 40.1 lists the various electrically assisted membrane processes with the type of effluents that could be treated most efficiently by each process. For most of the electrically assisted membrane processes (1 ), it is expected that the treatment of effluents would be most feasible when ion or particle concentration is high. These are also the effluents where alternative purification processes require a significant part of the process cost to be spent upon membrane... 

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